Work-clamp mechanism for sewing machines



May3, 1932. E. B. ALLEN WQRK CLAMP MECHANISM FOR SEWING MACHINES FiledApril 4, 19 30 3 Sheets-Sheet l Jwumtoz Edward bill/32a y 1932- E. B.ALLEN 1,856,900

WORK CLAMP MECHANISM FOR SEWING MACHINES Filed April 1950 s Sheets-Sheat2 E. B. ALLEN ,9

WORK CLAMP MECHANISM FOR SEWING MACHINES- 3 Sheets-Sheet 3 May 3, 1932.

Filed April 4, 1930 3 & WII IIIII ll Edward 15. Allen Patented May 3,1932 UNITED STATES PATENT OFFICE EDWARD B. ALLEN, F NEWTOWN,CONNECTICUT, ASSIGNOR TO THE SINGER .MANU- FAGTURIN-G- COMPANY, OFELIZABETH, NEW JERSEY, A CORPORATION OF NEW JERSEY WORK-CLAMP MECHANISMFOR SEWING MACHINES Application filed April 4, 1930. Serial No. 441,496.

The present invention relates to sewing machines and is herein shown asembodied in a buttonhole sewing machine of the full-automatic type, i.e., a machine which, when started, will perform all of its operationsautomatically in proper sequence and then come to rest. 7 v

The invention has for an object to improve the construction and mode ofoperation of,

0 sewing machines of the group-stitching type having a work-clamp, andparticularly to provide an improved construction of workclamp mechanismfor such machines.

The invention consists in the devices, combinations, and arrangements ofparts hereinafter described and claimed.

The several features of the invention and the advantages attainedthereby will be readily understood by those skilled in the art from thefollowing description taken in connection with the accompanying drawingswhich illustrate the several features of the invention as embodied in abuttonhole sewing machine. Fig. l is a side elevation of the machine.Fig. 2 is a horizontal section through the bracket-arm standard of themachine, showing the sewing machine bed and associated mechanism inplan. Fig. 3 is a side elevation of the work-clamp of the machine. Fig.4 is a disassembled perspective view of certain elements of thework-clamp. Fig. 5 is a trans verse vertical section through the machinebed, looking toward the bracket-arm standard, and Fig. 6 is a transversevertical section through. the work-clamp, taken on the line 66, Fig. 2.

The sewing machine illustrated herein is constructed substantially inaccordance with the disclosure of the application of Edward E. Allen,Serial No. 400,767,1iled Oct. 19, 1929. The machine is constructed witha bed 1, from whichrises the standard 2 of the bracket-arm 3 terminatingin the head 4. The stitch-forming mechanism comprises the reciprocatingand laterally vibrating needle 5 andcooperating shuttle 6. which areoperated as usual by the main-shaft 7 to make the usual zigzagbuttonhole overseam commonly used in so-called straight buttonholes.

The period of operation of the stitch-forming mechanism is controlled bythe usual stop-motion device including the tilting stopmotion lever 8,fulcrmned on the trunnionscrews 9, and carrying the upwardlyspringpress'ed stop-plunger 10 adapted to enter a notch in the stop-cam11 running with the main-shaft T. The stop-motion lever 8 is tilted torunning or dotted-line position, Fig. 1, by a down-pull on the startingrod 12connected at 13 to an arm 14 rigid with andextending forwardlyfrom the stop-motion lever 8. The rod 12 is released to stop thestitcheforming mechanism by the action of a tripping point 15 ontheusual feed-wheel 16 which runs with. the stitch-forming mechanism.When the stitching operation is completed, the tripping point 15 engagesand swings a lever 17 which, inturn', trips the latch 18, Fig. 5, fromengagement with the block 19 on theloperating lever '20, thus allowingthe rod 12 and stop-motion lever 8 to return from running or dotted lineposition, Figs. 1 and '5, to full line or stopping position.

The work isheld in a work-clamp which is moved longitudinally andlaterally over the bed 1 by the usual connections with the feedwheel 16,to place the stitches around the buttonhole. The work clamp comprisesthe usual lower work-supporting plate 21 and upper clamping foot 22which, unlike the construction disclosed in said Allen copendingapplication, is not mounted directly upon the main upper clamp-ljever23, but is carried instead by a supplemental lever 24 disposed beneaththe main upper clamp-lever 23; the levers 23 and 24- b-eingindependently fulcrumed preferably upon the same fulcrum pin 25 which isfixed by the screw 26, Fig. 6, in the ears 27 rising from a plate 28screwed to the lower clamp-plate 21. Referring to Figs. 4 and 6, it willbeseen thatthe main upper clamp-lever 23 has fixed to it a downwardlyand forwardly extending block 29 apertured at 30 to rock upon thefulcrum pin 25 between the supporting ears27, while the supplementalupper clamp-lever 24 has fixed to it the spaced ears 31 which areapertured to receive and rock upon the fulcrum-pin 25 at the outer sidesof the supporting ears 27. A stud-screw 32, Fig. 3, fixed to thesupplemental upper clamp-lever 24 rises through a clearance aperture 33in the main upper clamp-lever 23 and has interposed between its head andthe main clamp-lever 23 a relatively weak compression spring 34 whichtends to maintain the lever 24 in contact with or parallel to the mainlever 23, as shown in full lines in Fig. 3.

The tail 23 of the main upper clamp-lever 23 extends rearwardly under aroller-stud 35 carried by the vertically disposed slide-bar 36, Fig. 5,formed in its upper end with a slot 37 entered by a screw 38 threadedinto the clamp-lifting rock-arm 39 fulcrumed to turn upon and relativeto the usual stop-motionoperated rock-shaft 40 mounted horizontally atthe side of the standard 2 and common to machines of the straightbuttonhole sewing engaging under the screw 38, operatively couples theslide-bar 36 to the rock-arm 39 for operation by the latter. Thescrew-pin 44, constituting the lower end of the slidebar 36, is guidedin the stationary arm fixed to the bed 1. The rock-arm 39 is connectedby the chain 46 to the ball crank-pin 47 on-the gear 48 fixed to theshaft 49 of a mechanical machine-operator fully disclosed in the saidAllen copending application. The rock-lever 20, Fig. 5 is also connectedto the ball crank-pin 47 by means of the link 50.

Rising from the lower clamp-member 21 is a vertical post 51 which passesthrough clearance apertures 52, 53 in the respective upper clamp-levers24, 23, and is surrounded by a comparatively strong spring 54 whichpresses downwardly upon the clamp-lever 23 and forces the clamp-foot 22into clamping engagement with the work. A clownpull on the chain 46,therefore, forces the roller stud 35 downwardly upon the tail 23 of themain upper clamp-lever 23 and raises the .front end of the clamp-lever23 against the pressure of the spring 54 and opens the workclamp. Whenthe down-pull on the chain 46 is relieved, the spring 54 closes the workclamp.

The shaft 49 carrying the ball crank-pin 47 is journaled in the frame 55of the automatic machine operator which is stationed on the power-bench56, alongside the sewing machine. There is also journaled in the frame55 a driving shaft 57 carrying a pinion 58 of one-half the size of andmeshing with the gear 48.- The ball-crank pin 47 is thus given asemi-rotational impulse with the shaft 49 for each complete rotation ofthe driving shaft 57. The shaft 57 is connected through a manuallycontrolled one-rotation clutch-device including the usualclutch-controlling clamp.

fice for the purposes of the present disclosure to explain that the gate59, which is fulcrumed 0n the vertical stud-pin 59", may be swunginwardly about the pin 59 by a connection with the finger startinglever'60 to initiate one revolution of the shaft 57 to start the sewingmachlne. This initial revolution of the shaft 57 carries the ballcrank-pin 47 from its lowest position, Fig. 5, to its highest position(not shown). This movement of the crank-pin 47 relieves the pull on thechain 46 and allows the spring 54 to close the work- Italso acts throughthe link 50 and lever 20 to pull down on the rod 12 and start thestitch-forming mechanism. Y

\Vhen the sewing is completed, the action of the stop-motion device, inarresting the stitch-forming mechanism, imparts the usual rockingimpulse to the shaft 40 to which is fixed an arm 61 having abar-connection 62 for again shifting the gate 59 to initiate a secondrevolution of the driving shaft 57 which causes the ball crank-pin 47 tomove from its highest position back to its lowest position, Fig. 5, andopen the work-clamp. The connection of the gate59 with the fingerstarting lever includes the bell crank-lever 63 and the wire link 64. v

The mechanism so far described is, with the exception of thesupplemental upper clamp-lever 24, constructed substantially inaccordance with the disclosure of said Allen copending application. Inthe machine of said copenfding application the clamp-foot 22 isautomatically raised when the machine comes to rest and is automaticallylowered when the machine is started. It requires no effort on the partof the operator to manipulate the work-clamp against the relativelyconsiderable pressure of the clamp-closing spring 54.

For certain classes of work it is desirable to use the rectangularopening 22 in the clamp-foot 22 as a sight or guide to the accuratepositioning of the work in the workclamp, and the clamp-foot best servesas an accurate guide when in lowered position. The present improvementpermits the clamp-foot to be pulled downwardly upon the work to serve asa sight in locating the work before the machine is started and while themain clamp-lever 23 is in clamp-opening posit-ion, Fig. 3. There isfixed to the supplemental clamp-lever 24 a lateral arm 65 to which isconnected a treadle-chain 66 by means of which the supplementalclamp-lever 24 may be swung from full line to dotted line position, Fig.3, to lower the clamp-foot 22 into sighting or gaging position beforethe operator presses upon the starting button 60. This preliminarymovement of the supplemental lever 24: and foot 22 requires littleettort on the part of the operator as it is resisted only by the weakspring 34. As soon as the machine is started, the pressure of the heavyspring 54 is brought to bear upon the clamp-foot 22, as will be readilyunderstood.

Having thus set forth the nature of the invention, what I claim hereinis:

1. A work-clamp for sewing machines comprising a lower clamp-member,main and supplemental clamp-levers carried by said lower clamp-member, aclamp-toot carried by said supplemental clamp-lever, automatic means foroperating said main clamp-lever, and manually operated means for movingsaid supplemental clamp-lever toward the lower clamp-member, and arecovery spring for lifting said supplemental clamp-lever.

2. A work-clamp for sewing machines comprising a lower clamp-member,main and supplemental clamp-levers carried by said lower clamp-member, aclamp-toot carried by said supplemental clamp-lever, automatic means foroperating said main clamp-lever, and a pull-chain and recovery springconnected to said supplemental clamp-lever.

3. A sewing machine work-clamp comprising a lower work-supporting plate,a main upper clamp-lever fulcrumed on said plate, a supplemental upperclamp-lever tulcrumed for movement independently of said main upperclamp-lever, manually operated means for moving said supplementalclamp-lever toward the work-supporting plate independently of said mainclamp-lever and while the latter is in clamp-opening position and arecovery spring for lifting said supplemental clamp-lever.

4. In a sewing machine, stitch-forming mechanism, a stop-motion device,a workclamp, a clamp-closing spring, automatic means for opening thework-clamp against the force of said clamp-closing spring, and manuallyoperated means independent of said spring for closing the work-clampbefore the machine is started.

5. In a sewing machine, a work-clamp having a lower work-supportingplate, an upper clamp-foot, an automatically operated main clamp-closinglever, a supplemental clamplever carrying said clamp-foot, and manuallyoperated means connected to said supplemental clamp-lever to lower saidclamp-toot, said main lever being arranged to press directly upon saidsupplemental lever in applying clamping pressure to said clamp-foot.

6. A sewing machine work-clamp comprising, a lower clamp-member, mainand supplemental clamp-levers carried by said lower clamp-member, aclamp-foot carried by said supplemental clamp-lever, a relatively strongclamp-closing spring acting upon said main clamp-lever, a relativelyweak recovery spring acting upon said supplemental clamplever, automaticmeans for operating said

